An electromechanical system in one example measures a parameter. The electromechanical system may comprise a microelectromechanical system (“MEMS”) accelerometer or gyroscope that measures the parameter. For example, the accelerometer measures an acceleration and the gyroscope measures an angular rate (e.g., rotation). The gyroscope in one example comprises a vibrating beam with high Q degenerate fundamental modes of vibration. For example, high Q vibrating beams require little energy to sustain vibration. The vibrating beam in one example is employable for high performance closed loop angular rate sensing. The vibrating beam in another example is employable for lower performance open loop angular rate sensing. The mathematical model of the symmetrical vibrating beam is in many aspects similar to a vibrating ring or hemispherical resonator gyroscope (“HRG”). The analytical similarity to the hemispherical resonator gyroscope indicates that the vibrating beam gyroscope has the potential of achieving similar performance.
Drive components coupled with the vibrating beam cause a first oscillation of the vibrating beam. An angular rate of the vibrating beam and the first oscillation induce a Coriolis force on the vibrating beam. For example, the angular rate is about the longitudinal axis of the vibrating beam. The Coriolis force causes a second oscillation of the vibrating beam. The second oscillation is substantially perpendicular to the first oscillation. Feedback components in one example provide feedback on a magnitude of the first oscillation to the drive components for regulation of the first oscillation. Pickoff sensor components sense the second oscillations and apply control signals to null the pickoff signal. The control signals are a measure of the magnitude and polarity of the angular rate of the vibrating beam.
Coriolis Vibratory Gyros (CVG) based on the free-free vibrating beam are currently used to sense angular rotation rate. The beams are typically supported at the nodal points of the beam to minimize the coupling of the vibration energy to the mounting base. The coupling of vibration energy to the mounting base reduces the Q of the resonant frequency of the beam and introduces sensitivity to variation in the mechanical impedance of the mounting.
There is a need in the art for an improved CVG that minimizes coupling of vibration energy to a mounting base for use in high performance vibrating beam gyros which require high Q and low mounting sensitivity.